Loki Password Stealer (PWS)

"Loki Bot is a commodity malware sold on underground sites which is designed to steal private data from infected machines, and then submit that info to a command and control host via HTTP POST. This private data includes stored passwords, login credential information from Web browsers, and a variety of cryptocurrency wallets." - PhishMe

Loki-Bot employs function hashing to obfuscate the libraries utilized. While not all functions are hashed, a vast majority of them are.

Loki-Bot accepts a single argument/switch of ‘-u’ that simply delays execution (sleeps) for 10 seconds. This is used when Loki-Bot is upgrading itself.

The Mutex generated is the result of MD5 hashing the Machine GUID and trimming to 24-characters. For example: “B7E1C2CC98066B250DDB2123“.

Loki-Bot creates a hidden folder within the %APPDATA% directory whose name is supplied by the 8th thru 13th characters of the Mutex. For example: “%APPDATA%\ C98066\”.

There can be four files within the hidden %APPDATA% directory at any given time: “.exe,” “.lck,” “.hdb” and “.kdb.” They will be named after characters 13 thru 18 of the Mutex. For example: “6B250D.” Below is the explanation of their purpose:

FILE EXTENSION FILE DESCRIPTION.exe A copy of the malware that will execute every time the user account is logged into.lck A lock file created when either decrypting Windows Credentials or Keylogging to prevent resource conflicts.hdb A database of hashes for data that has already been exfiltrated to the C2 server.kdb A database of keylogger data that has yet to be sent to the C2 server

If the user is privileged, Loki-Bot sets up persistence within the registry under HKEY_LOCAL_MACHINE. If not, it sets up persistence under HKEY_CURRENT_USER.

The first packet transmitted by Loki-Bot contains application data.

The second packet transmitted by Loki-Bot contains decrypted Windows credentials.

The third packet transmitted by Loki-Bot is the malware requesting C2 commands from the C2 server. By default, Loki-Bot will send this request out every 10 minutes after the initial packet it sent.

Communications to the C2 server from the compromised host contain information about the user and system including the username, hostname, domain, screen resolution, privilege level, system architecture, and Operating System.

The first WORD of the HTTP Payload represents the Loki-Bot version.

The second WORD of the HTTP Payload is the Payload Type. Below is the table of identified payload types:

The 11th byte of the HTTP Payload begins the Binary ID. This might be useful in tracking campaigns or specific threat actors. This value value is typically “ckav.ru”. If you come across a Binary ID that is different from this, take note!

Loki-Bot encrypts both the URL and the registry key used for persistence using Triple DES encryption.

The Content-Key HTTP Header value is the result of hashing the HTTP Header values that precede it. This is likely used as a protection against researchers who wish to poke and prod at Loki-Bot’s C2 infrastructure.